Preheat oven to 350 degrees and lightly grease an 8x4-inch or 7x4-inch loaf pan with avocado oil or olive oil.
In a large mixing bowl, whisk together the blanched almond flour, ground flax seeds, sea salt, baking powder, xanthan gum, and sweetener (if using).
In a large mixing bowl, combine the egg whites and cream of tartar (if using). Be sure the bowl is large enough because the egg whites will expand a lot.